Having trouble understanding some of the details of R-CNN (first one)
Yes, your description is mostly aligned with the original paper. However, Figure 1 shows they use features from the second fully connected layer (not the last convolutional layer).
Yes. The training is performed by exploiting hand-annotated bounding boxes. If a proposal has IoU less than 0.3, then it is considered as a negative example (cf. section 2.3).
No. Appendix C explains that box regression parameters are learned separately from the SVM model.